


Mac and Dee Lend a Helping Hand

by usuallysunny



Category: It's Always Sunny in Philadelphia
Genre: Angst and Fluff, Dirty Talk, F/M, Friendship, Hurt/Comfort, Mac and Dee Miss Dennis, Mac is still gay, Pegging, Pre S13, Smut, Unhealthy Coping Mechanisms, hints of twincest, it's really all about dennis, post s12
Language: English
Status: Completed
Published: 2019-02-04
Updated: 2019-02-04
Packaged: 2019-10-20 10:29:37
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,912
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17620760
Author URL: https://archiveofourown.org/users/usuallysunny/pseuds/usuallysunny
Summary: Mac and Dee have never understood each other, not really. But now Dennis is gone and they're all that's left.Agreeing to bang one of your best friends while he thinks about your twin isn't exactly healthy... but it's something.





	Mac and Dee Lend a Helping Hand

**Author's Note:**

> Because it's always fun to try out unusual pairings! Mac is still very much gay and very much in love with Dennis.

Dee gazes at the tiny shot glass on her kitchen table, her eyes narrow and contemplative.

She hesitates for only a second before she swiftly grabs it and knocks it back.

" _Ah, goddamn._ " She hisses as the alcohol scorches down her throat, leaving a pleasant burn in its wake. She slams the glass down so hard, she's almost surprised it doesn't shatter.

Judging by Mac's wide eyes and arched brow, he's surprised too.

"What?" She snaps, vision slightly blurred. "If we're gonna do this, there's no way I'm gonna be sober."

She uses one knuckle to push the other shot glass towards him.

"We've been drinking for five hours, Dee." He informs her but doesn't hesitate to take the shot too. He doesn't grimace as much as she does - on account of him being a massive badass who can handle his liquor - but he looks a hell of a lot more nervous.

"Yeah, well." She stands up and the rickety chair scrapes on the floor. "That's how long it takes for you to become  _even remotely_  attractive to me."

"Like you're some sort of oil painting, you gross bitch." He fires back, suddenly angry for no reason.

Dee rolls her eyes, completely unfazed. She's used to his temper tantrums. In-fact, she's almost jealous. Sure, sometimes they're misguided... random bursts of frantic energy... but Mac feels every emotion that rockets through his body like a hurricane.

Dee only  _wishes_ she could feel that deeply. Her capacity for excitement, for warmth, has long been burned out of her.

"We doing this or not?"

Mac swallows, pausing for a beat. From where he's sitting and she's standing, he can understand how Charlie was intimidated by her larger frame. So he stands too, because he's huge and jacked and hot as shit now.

He could lift her whole bony body with one hand if he wanted to, but that's not what he's here for tonight.

The thought of what he  _is_  here for, the stupid agreement they've drunkenly come up with (no creepy, official documents though because they're not  _him_ ) - has his mind flooding.

_What are they doing?_

_What were they thinking?_

_What—_

"Boobs." He suddenly blurts out, his mouth dry.

Dee's not giving him any chance to think, to change his mind, because she's standing in-front of him without a shirt, her hands on her hips.

"Shall I keep going?" She puts on this weird, raspy voice that immediately has Mac confused. Her hands go behind her back to her bra clasp and her eyes seem to twinkle. "Or do you wanna do the rest?"

"Oh my god." He mutters as he realises what she's going for. Goddamn, she's a terrible actress. He takes a step forward and shakes his head. "Don't try to be sexy, Dee. Jesus Christ."

Her jaw tightens and her cheeks explode into heat.

"If you're gonna humiliate me - like you  _always_ do - you can just fuck off." Her voice is shrill, acerbic. "I'm doing this for you."

Mac softens slightly and comes to stand in-front of her. His eyes flicker the length of her torso and his fingers twitch - not because he wants to touch her, but because he doesn't.

"Sorry." He grumbles. "You're right. This is about helping each other."

"Yes it is." She snaps back too quickly. "Now put your hands on my waist."

"Do I have to?"

She rolls her eyes and grabs his wrists, roughly placing them on her skin. "How are we gonna fuck if you won't touch me?"

Mac's expression twists into a grimace.

"Goddamn it, Dee. Some finesse,  _please._ "

"The fact that you even  _know_ that word demonstrates why we're here. Who taught you it?"

Mac's stomach drops and his brows draw into a frown.

"You know who."

His voice is quiet, lined with vulnerability. His fingers twitch around her waist and Dee almost feels bad.

"Hey, don't be sad, boner." She tries to lighten the mood. "Just think of this as a business transaction. I scratch your back, you scratch mine. Except, ya know, " _I_ " will be a dildo and your " _back_ " will be your ass. And " _mine_ " is my pussy and " _you_ " is your mouth."

Mac's face draws a blank and his mouth gapes open and his eyes kind of squint.

"Huh?"

Dee lets out a little frustrated noise and a look of impatience flickers over her features. It's the first thing that kind of works for Mac, because she looks so much like the person he wants her to emulate.

"I'm gonna peg you and you're gonna lick me out."

Mac's eyes flash with understanding. "Right yeah. We've already agreed to that. I dunno why we're going 'round in circles."

A barrage of insults rest on Dee's tongue but she bites them back. She sends him a forced, tight-lipped smile instead.

"Okay. Let's do this."

She pulls on his forearms, forcing him to wind his arms tighter around her while her own find refuge around his neck. Leaning forward, she wets her lips and seeks out his slightly-parted mouth.

"Whoa." He jerks his head back. "What are you doing?"

"I thought we'd start with some kissing?"

Mac's face seems to pale. "Isn't that... kinda intimate?"

Dee stares at him, dumbfounded.

"More intimate than eating pussy?"

He tips his head to the side, almost like he's conceding, but she can see he's still reluctant.

But Dee  _likes_  kissing. It sets the mood and makes her feel all cute and warm inside. The corners of her lips twitch into a devious smile as she puts her first plan in motion.

"Ya know..." She starts in a deceptively innocent drawl, "Dennis and I used to practice kissing all the time. So I know his technique. I know what he likes and doesn't like. I know how much pressure he wants and how much tongue he uses. It'd be just like kissing him."

Mac's eyes seem to darken -  _damn, he's easy_ \- but something else breaks through the lust-filled haze.

"You used to  _kiss_?" His tone is equal parts disgust and jealousy, "That's so gross."

"We're  _twins._ We grew up together. It's totally normal for kids to experiment."

_That's the line she's always given herself and she's sticking to it._

She doesn't have to worry about how she views her childhood escapades because the explanation is obviously good enough for Mac. Desperate for any part of Dennis, he crashes his mouth to hers. He kisses her fiercely, his tongue swiping over her bottom lip like he's trying to taste whatever scraps might be left there.

It takes her off guard but it's not exactly unpleasant. His tongue continues to coax and she opens her mouth. He licks inside, his arms pulling her flush against his strong chest, and she's shocked to feel tiny sparks of lust snap at her heels. She's not sure what she expected –  _not that she ever thought about it at all_ – but Mac's a good kisser. Just the right amount of pressure, the right amount of teeth and tongue.

She pushes back, suddenly wanting to prove her skills, and she's not sure if she's getting Dennis' technique right, but Mac lets out a little moan regardless.

If she could take a moment to think, she'd consider how it's  _Mac_ moaning into her mouth.

 _Mac,_  who coined the "bird" nicknames that make her life a misery.

 _Mac_ , whose shoulder she pissed on when they were stuck in a water slide.

 _Mac,_  who's completely, hopelessly, pathetically in love with her brother.

But she doesn't want to think about what a fucked up web she's weaving - because his mouth is soft and he tastes like whiskey and something sweeter and she hasn't been kissed in  _so long._

His soft tongue tangles with hers and she feels a spark of excited anticipation for how that's going to feel between her legs.

Maybe she should feel guilty. She knows Mac's gay and the thought of them together probably makes him want to heave -  _I'd rather get shot in the face,_ he'd charmingly once said - but she doesn't work for free. It's not like he's never done it before. Before he came out, his conquests with women were numerous and varied. If he can fuck Margaret McPoyle -  _twice_ \- he can fuck her.

He should feel fucking _grateful_ to have a strong, powerful woman like Dee in his bed. 

And if she's going to undertake the monumental task of strapping on a dildo and fucking him with it while he gets off to her brother, she's damn well going to get an orgasm in return. It's only fair, right?

Besides, she can feel the insides of her thighs getting slick from the movement of his surprisingly adept tongue and she's not passing up an opportunity to get off. She doesn't care much for the pleasure of her sexual partner.

Dennis doesn't either, so maybe that will work.

She breaks away from his mouth and takes a deep breath.

"I guess we should..." Her big hands fly between them, gesturing to their clothes, "...get undressed?"

Mac swallows, clearly nervous. His hands go to the hem of his shirt and he pulls it off quickly, like he wants to get this part over with.

"Holy fuck." Dee breathes, her eyes widening. Her hands go to his sculpted abs and they twitch under her cold fingers. "Mac, you're so fit now. You look incredible."

She's not trying to seduce him or be sexy or _any_ of that shit; she's literally impressed. It's been a while since she banged such a beefcake. 

"You think?" Mac's so predictable, soft like a little puppy, and he relishes in the attention. 

"Yeah." She breathes out, "Absolutely. Now take my bra off."

His eyes kind of widen before he nods, like he needs to psyche himself up. His hands travel behind her back, fumbling with the clasp, and she watches his face unattractively twist in concentration.

She rolls her eyes but doesn't know why she's surprised.

After-all, he's still Mac and she's still Dee and they'll never  _really_ understand each other. Never really fit.

"How the fuck d'ya work this thing?"

" _Jesus Christ._ It's like you've never fucked a girl before."

He quirks a brow and gives her a deadpan stare. "Is that what you call yourself?"

"Eat a dick."

"I dunno why you wear this thing anyway," He lets out a sound of triumph as he finally unclasps the bra and throws it to the side. "Not like you need it. You have, like, no tits."

"Just how you like it."

It probably speaks to how fucked up she is that this offensive back and forth... it just turns her on more.

Things move a bit quicker then, their bodies laced with shame and pain and an eagerness to forget. Before Dee knows it, Mac's on her bed, laying on the sheets she hasn't washed since he and Dennis left them. She's not sure why, and she won't dwell on it. 

He's pulling at his dick, movements a little frantic and eyes screwed shut. With her head slightly tipped to the side, she notices how nice his cock is. It's a good length, a good width, and in another life, she would've definitely gone to town on it. Alas, it's not meant to be and she just reaches for the strap on he's provided her instead.

Her head practically spins from the romance of it all. 

Mac's other hand flies to his face and he drapes the back of it over his forehead. 

"Can you hurry up?" He bites out, probably unsure of his ability to maintain a hard-on in her presence.

"Yeah, yeah..." Dee rolls her eyes as she adjusts the harness around her bony hips. She pulls it tight and climbs on the bed, marvelling at the feeling of the purple cock bobbing between her legs. 

Mac's eyes darken at the sight, brown morphing into black. Dee reaches over him, fetching the bottle of lube she keeps in the bedside table. She registers the bob of his Adam's apple as he swallows, watching her wet her fingers and then the head of the dildo.

"You ready?" 

"Yeah." He rasps and it sounds like he's been screaming. He clears his throat and Dee gestures for him to turn around. "Wait—" 

Dee sighs, impatient. "What?"

"I, uh, I need one more thing."

Her eyes widen and her mouth falls open.

"You've  _got_ to be fucking kidding me."

"I was just..." A bright flush rises up his cheekbones and Dee raises a brow, confused. "I was wondering if you could, like... be mean to me."

"Huh?"

"Like, a bit cruel. Like, insulting..."

"Like Dennis?" Dee says dryly.

Mac lowers his gaze, sheepish and nervous and a little ashamed.

"It's why it had to be you. I could easily bang some random dude or even convince Charlie to do it but... no-one  _knows_ him like you do. You're basically the same person, just without a dick."

Dee quirks a brow to the one she currently has hanging between her legs.

"So basically, you chose me because I'm a bitch."

Mac shrugs unapologetically. "I'll make it real good for you after."

Dee pauses before conceding with a sigh. If there _is_ a Hell and she wasn't headed for it before, she definitely is now. 

"Fine. Jesus goddamn Christ. Turn over."

Mac does as he's told and suddenly Dee's faced with his bare ass and her own reluctant desire. She kneels behind him and watches his hands fist the sheets until his knuckles turn white. 

She decides to just pull the band aid off, so to speak. 

"Look at you..." She tuts, shaking her head and biting the inside of her cheek as she grabs the dildo and starts to push it inside, "So desperate for Dennis' dick."

 _Jesus Christ. This is fucked up,_ she thinks, even as heat pools in the pit of her belly. It  _is_ fucked up - that's her  _brother,_ after all - but maybe it's okay because she's fucked up too. And Dennis has played a huge part in that, has ruled her for most of her life. 

Tied together since the womb, he's always loomed over her like a dark shadow, a bad dream. In many ways, he owns her just as much as he owns the man whimpering in-front of her. She hates him so much it makes her sick and she hates that she misses him even more. 

"Please... fuck me..." Mac is moaning, moving his hips, trying to pull her inside. 

"Shut up." She barks, her hands resting on his ass cheeks as she slowly pushes inside. Mac keens against her, letting out a choked moan as she finally buries the dildo to its hilt. 

She begins to move, the friction on her clit adding to the pleasure of being in control. She moves her hips and squirts a bit more lube on the dildo and his ass when she finds a little resistance.

"You're so tight, Mac." She says, her hands moving to his hips. "Have you been saving yourself for him? That's so pathetic."

Maybe she's getting soft in her old age but the words feel wrong on her tongue. She feels... bad, guilty. She knows how much Mac cares and maybe  _she's_ never cared before, but she does now and she doesn't particularly want to hurt him. 

"Fuck, yeah.... _only you_..." But Mac is groaning under her, his right hand letting go of the sheets beside him to travel under his body. 

 _He wants this_ , she reminds herself as he pulls at his dick and rests his brow on his left forearm. The sounds of him jerking off add to the obscene slapping of her hips and she fights to catch her breath. 

"You're so pathetic." She sneers, trying to sound like Dennis. "So desperate. He'd  _never_ touch you. You're so beneath him, it's not even funny."

"Shit, yeah. That's it." Mac's babbling, eyes screwed shut as she moves her hips faster. "More. Please, _De—_ " 

His breath catches and a strangled noise, a mixture of her name and her twin's, falls from his lips.

It's fitting, in a way.

She never has been able to tell where Dennis ends and she begins.

"Such a slut." She's getting into it now; a perverse part of her loves having him at her mercy. She's tired of being the Gang's plaything, tired of the joke always being on Dee. Mac almost sobs, his body trembling, and she feels strong, powerful, in charge. "Dennis' little slut. Jesus, you're so embarrassing, Mac. I wish he still had those stupid cameras set up everywhere. I would love to show him this, show you begging for his cock."

"No..." Mac whines. "Please, don't. Don't show him, Dee. Please."

He sounds a different kind of desperate now and she feels a tiny twinge of guilt.

"As if." She snorts, trying to play it off. "I would never debase  _myself_ like that. You're so dumb, getting fucked by a girl you call ugly... a bird... gross. Who's gross now, huh?"

Really, Dennis would love this. She knows that. He would love seeing how much power he has over them; how, even thousands of miles away, he still controls everything they do. Dee can just see him now, smirking and rewinding the tape over and over, just to see Mac's cry as he comes with his name on his lips or how desperate Dee is for any scraps of his attention.

"Just fuck me harder." Mac pants, his hips beginning to move in time with hers. She hears, more than sees, him tugging faster at his dick. She can see the corded muscles in his back and shoulders pulling tight and she senses that he's close. 

Her lungs burn and she wipes the sweat from her brow.  _Jesus Christ, this is hard work._

She pushes through, lust and sadness and a million other emotions she can't even begin to decipher coursing through her blood. Suddenly, she wants this over. 

"You're gonna come, aren't you?" She mocks, angling the dick so she hits his prostate. It clearly works because Mac lets out a cry, almost sobbing with pleasure. "Gonna come for a guy who couldn't care less about you. He left, Mac. He left us." He throat burns and she blinks back hot tears of frustration. "You'll never be good enough for him. He'll  _never_ love you, the way you love him."

"Fuck,  _Dennis..._ " Mac comes with a grunt, spilling hot and sticky over his hand and the comforter. Dee rocks into him a few more times, her heart pounding from the physical exertion and something else she can't put her finger on. 

She pulls out and his body shutters, a small whine leaving his lips. She collapses on her haunches, exhausted, but she wastes no time in removing the harness. A strange panic grips at her and she wants it off. She tosses it to the side like it's burned her.

She's  _going_ to yell at him for not putting a towel down, going to tell him she doesn't want his gross cum all over her sheets.

She's  _going_ to snap her fingers, spread her legs and tell him to get to it - that it's her turn.

But then he's sitting cross-legged over the damp patch and looking at her, all sheepish and shy and scared. Dee thinks he looks like a stupid kid. A stupid, naive baby. 

"You're right." He whispers and his eyes glisten with tears. "He'll never love me, will he?"

She stares at him, her expression cold and blank.

"No." She says simply. "He'll never love anyone."

Her eyes burn then, for Mac and how much he's hurting but mostly for herself - for as much as she knows that's true, she also knows that they'll never love  _anyone else._

She's just swallowing past the lump in her throat - _she won't cry any more for that asshole_ \- when Mac's suddenly grabbing at her thighs. She lets out a squeal as he pulls her into his lap, before twisting them around until her head's on the pillow. He covers her with his body and he's all marble, strong and smooth. He moves down her body, fingers finding her wetness.

For a minute, it's exhilarating. She hasn't been fucked in so long and she's used to being the bigger one - taller, leaner, stronger. Mac's so muscly now, him throwing her around makes her feel cute and girly and tiny like Thumbelina. 

He settles between her thighs and spreads them. He looks at her for a moment, his expression indecipherable, before he leans down and prepares to return the favour.

Again, she hasn't had sex in a _very_ long time. She hasn't felt anyone's mouth down there for even longer. Until the day she dies, Dee will insist she deserves a fucking medal for what she does next. 

Mac only gets in one hot lick before she rewards him by pulling his hair, tugging him up to her level.

"Ow!" He yells. "What the fuck are you doing?"

It's a good question and she rubs a tired hand over her face. She looks at him again, at how his big, sad eyes are still shining with wet tears, and she gives a heavy sigh. 

She can't do this. She knows she's a bitch, but she never thought she was a _"force your almost-in-tears gay friend to go down on you"_ bitch. Sure, she's frustrated and turned on, but she's upset and tired too. It just doesn't seem right, so she shrugs and tries to look casual.

"I'm tired." She tries to play it off. "And totally not in the mood after that shit show. Let's just forget it."

He stares at her, open mouthed.

"Are you sure? I mean, you did that for me and—"

"Yeah, I don't want to talk about it." She says because she really doesn't, "I just want to sleep."

Mac shifts slightly but doesn't put up a fight. She'll never admit the real reason she doesn't want it - that she actually _cares_ about him and thinks he deserves better than her asshole brother - and he'll never ask. 

She lays down, turning her back to him and squirming away from the wet patch on the bed. She screws her eyes shut, silently wills him away, and hopes that's the end of it. 

But Mac doesn't go away. Instead, he lays down behind her, next to her, and hesitantly wraps his arm around her. 

"Can I maybe stay here tonight?" He asks nervously and his hand reaches for hers. She's too tired to argue and he entwines their fingers. "I don't think I can bear to be alone."

She doesn't answer, but squeezes his hand a little tighter. 

She reaches over and turns off the lamp. The darkness covers them like a blanket, strange but softly comforting.

They're silent for a moment before Dee feels a wetness on her neck. 

"Mac..." Her stomach twists and her mouth suddenly feels very dry, "I didn't mean it, you know. All that shit I said..."

"Yeah, yeah." Mac scoffs, all fake bravado, "I'm only crying because you're so ugly."

She rolls her eyes in the dark. "Okay."

"Hey, Dee?"

Her eyelids flutter as sleep threatens to overcome her.

"Yeah?"

"Thank you."

His voice is soft, unsure, and she doesn't know what he's thanking her for. 

She sure as shit doesn't feel any better and she's certain he doesn't either. 

**Author's Note:**

> this is so gross and sad, i'm sorry, don't hate me :)


End file.
